Wireless electronic devices typically handle one or more cellular communication standards, and/or wireless connectivity standards, and/or broadcast standards and, for that purpose, the devices incorporate a radiating system capable of operating in the one or more frequency bands in which said standards are allocated, with an acceptable radioelectric or radiofrequency performance (in terms of, for instance, reflection coefficient, standing wave ratio, impedance bandwidth, gain, efficiency, or radiation pattern).
Besides radiofrequency performance, one of the current limitations of the prior art is that generally the antenna system is customized for every particular wireless handheld or portable device model while requiring features such as small dimensions and reduced interaction with human body and nearby electronic components. The mechanical architecture of each device is different and the volume available for the antenna severely depends on the form factor of the device model together with the arrangement of the multiple components embedded into the device (e.g., displays, keyboards, battery, connectors, cameras, flashes, speakers, chipsets, memory devices, etc.). As a result, the antenna within the device is mostly designed ad hoc for every model, resulting in a higher cost and a delayed time to market. In turn, as typically the design and integration of an antenna element for a radiating structure is customized for each wireless device, different form factors or platforms, or a different distribution of the functional blocks of the device will force to redesign the antenna element and its integration inside the device almost from scratch.
A radiating system for a wireless handheld or portable device typically includes a radiating structure comprising an antenna element which operates in combination with a ground plane layer providing a determined radiofrequency performance in one or more frequency regions of the electromagnetic spectrum. Typically, the antenna element has a dimension close to an integer multiple of a quarter of the wavelength at a frequency of operation of the radiating structure, so that the antenna element is at resonance or substantially close to resonance at the frequency of operation, and a radiation mode is excited on the antenna element. Due to given space limitations in the device and the necessity of providing operation in two or more frequency bands that, in some cases, are located in at least two separate frequency regions of the electromagnetic spectrum, the antenna elements usually present complex mechanical designs and considerable dimensions, mainly due to the fact that antenna performance is highly related to the electrical dimensions of the antenna element. Although the radiating structure is usually very efficient at the resonant frequency of the antenna element maintaining a similar performance within a frequency range defined around said resonant frequency (or resonant frequencies), outside said frequency range the efficiency and other relevant antenna parameters deteriorate with an increasing distance to said resonant frequency.
The integration of the radiating system within the wireless electronic device is also a key aspect in terms of the radioelectric performance (such as for example in terms of radiated power, received power, sensitivity), as once the radiating system is included inside the device, detuning of the radiating system and disruptions due to the electronic components and circuitry embedded in the device deteriorate its performance. Once the design of the electronic device is finished, fine adjustments or tuning of the performance of the antenna are quite limited or even unfeasible. A radiating system as described in the present patent application is intended to provide a solution in this regard, while featuring good radioelectric characteristics such as multiband and/or broadband behavior.
Some techniques for optimizing the broadband or multiband behavior of an antenna element, and/or miniaturizing the antenna element have been described in the prior art.
For example, commonly-owned U.S. Pat. No. 7,148,850 describes a family of antennas based on the geometry of space-filling curves. Also, commonly-owned U.S. Pat. No. 7,397,431 relates to a family of antennas, referred to as multilevel antennas, formed by an electromagnetic grouping of similar geometrical elements.
Another example is commonly-owned U.S. Pat. No. 7,315,289 which describes an antenna comprising at least two arms being coupled to each other through a region on first and second arms such that the combined structure of the coupled two-arms forms a small antenna with a broadband behavior, a multiband behavior or a combination of both effects. In said patent, the multiband response may be obtained by adjusting the length and size of the several-coupled arms, together with the spacing and size of the proximity region defined between the several arms, or by shaping at least one of the arms as a multiband antenna.
Commonly-owned patent applications WO2014/012842 and US2014/0015728 disclose wireless handheld or portable devices including very compact, small size and light weight radiation boosters operating in single or in multiple frequency bands. The entire disclosures of aforesaid application numbers WO2014/012842 and US2014/0015728 are hereby incorporated by reference.
Commonly-owned patent applications U.S. 62/028,494 and EP14178369 describe wireless devices including at least one slim radiating system having a slim radiating structure and a radio-frequency system, wherein the slim radiating structure includes one or more booster bars. The entire disclosures of aforesaid application numbers U.S. 62/028,494 and EP14178369 are hereby incorporated by reference.
Commonly-owned patent applications U.S. 62/152,991 and EP15165167 disclose wireless portable or handheld devices with a radiating system configured to transmit and receive electromagnetic wave signals in first and second frequency regions. The radiating system comprises a radiating structure comprising at least one ground plane layer and a radiation booster; a radiofrequency system; and an external port. The radiofrequency system comprises a matching circuit configured to provide impedance matching to the radiating structure, at the external port, in a first frequency region and in a second frequency region. The entire disclosures of aforesaid application numbers U.S. 62/152,991 and EP15165167 are hereby incorporated by reference.
Therefore, a wireless electronic device comprising a radiating system providing broadband or multiband operation without antennas that are geometrically complex or large would be advantageous. It would be also particularly advantageous that the radiating system featured good radioelectric performance with a relatively small ground plane, and that it supports flexibility for tuning and adjusting the performance taking in consideration all the elements included within the device which may detune the radiating system.